Influence of annealing on dielectric and polarization behavior of PVDF thick films

Abstract

The polyvinylidene fluoride (PVDF) thick film has been fabricated by a solution casting method. The fabricated film is subjected to annealing at 50, 90, 100, 110 and 130 °C for 5 h. The effect of annealing on structural, crystalline, dielectric and polarization behavior is investigated. The β-phase PVDF is found to coexist with α-phase for annealing temperature upto 100 °C, after that β-phase is converted to α-phase. The film annealed at 100 °C, exhibits enhanced permittivity, reduced tangent loss and enhanced polarization. The dielectric permittivity and tangent loss of film annealed at 100 °C are ~11 and ~0.025 respectively for the frequency range of 10 3 -10 5 Hz. The saturation polarization for this film is ~1.27 µC/cm 2 . The enhanced dielectric permittivity and polarization for the film annealed at 100 °C might be attributed to increase in crystalline α and β-phase interface as well as crystalline amorphous interface. The thick film of PVDF with improved dielectric and polarization behavior could be useful for high power electronics application.

Aligned P(VDF-TrFE) Nanofibers for Enhanced Piezoelectric Directional Strain Sensing

“…Compared with spin-coated P(VDF-TrFE) films, which require additional electrical poling to achieve high piezoelectricity [ 40 ], the P(VDF-TrFE) nanofibers are advantageous for excellent response without annealing. As shown in Figures 3c and 5f, the annealing process significantly enhanced the piezoelectric response, which was verified by previous studies for both PVDF and P(VDF-TrFE) [ 41 , 42 , 43 ]. Directional sensing is universal in biological sensory organs such as hair cells in the inner ear, lateral line neuromasts of fish, and mechanosensitive hair sensilla of insects [ 44 , 45 , 46 ].…”

Synergistic Effect Based on Enhanced Local Shear Forces in PVDF/TiO2/CNT Ternary Composites

“…As shown in Figure a, when the CNT content is lower than 2.5 wt %, the ε r of the composites is nearly independent of the frequency in the frequency range from 10 2 to 10 5 Hz. However, the ε r of the PVDF composites with 5 wt % CNTs sharply decreases with increasing frequency at below 10 3 and above 10 7 Hz, which are related to the interfacial polarization and the dipole-orientational polarization, respectively. , Meanwhile, the plateau that hardly varies with frequency shifts to the high frequency with the increase of TiO 2 and CNT concentration, compared to that of PVDF10T2.5C. This may be assigned to the formation of conductive pathways/networks and the limited PVDF chain motion. , The dielectric loss (tan δ) of the PVDF composites with a high fraction of CNTs exhibits a stronger frequency dependence than the composites with low level, as shown in Figure b.…”

“…However, the ε r of the PVDF composites with 5 wt % CNTs sharply decreases with increasing frequency at below 10 3 and above 10 7 Hz, which are related to the interfacial polarization and the dipole-orientational polarization, respectively. 42,44 Meanwhile, the plateau that hardly varies with frequency shifts to the high frequency with the increase of TiO 2 and CNT concentration, compared to that of PVDF10T2.5C. This may be assigned to the formation of conductive pathways/networks and the limited PVDF chain motion.…”

Optimization of a Soft Pressure Sensor in Terms of the Molecular Weight of the Ferroelectric‐Polymer Sensing Layer

“…[50] The larger the crystal region, the larger the crystallite size, and the higher the remanent polarization. [51][52][53] In terms of P(VDF-TrFE) molecular weight, it is expected that at P(VDF-TrFE) molecular weights of 300-440 kg mol −1 , the degree of crystallization is affected by the increased entanglement of polymer chains; [54][55][56] whereas at P(VDF-TrFE) molecular weights of 230-300 kg mol −1 , it is affected by the spherulite growth rate. [57,58] The spherulite growth rate is relatively low at lower molecular weights and, up to a certain molecular weight, a direct proportional correlation exists between molecular weight and the rate of spherulite growth.…”